Conditions InDepth: Heart Failure

Heart failure is a progressive condition in which the heart cannot pump enough blood to meet the needs of the body. When the heart fails to keep up with this demand, fluid can accumulate behind the failing heart chambers. In order to understand the types of heart failure, you should first understand how the heart, the center of the circulatory systems, works.

The heart has a right and left side, and each side has two chambers. The four chambers of the heart have specific functions:

Two upper chambers (atria/atrium)
—Receive blood from the body and empty the blood to the lower chambers.

Two lower chambers (ventricles)
—Receive blood from the upper chambers and pump blood back out to the body.

The right atrium receives blood from the body and empties it into the right ventricle. The right ventricle pumps the blood out to the lungs where carbon dioxide is exchanged for oxygen. The left atrium receives oxygen-rich blood from the lungs, then empties it into the left ventricle. The left ventricle is the strongest muscle/chamber in the heart and is responsible for pumping the blood back out to the body.

Heart failure is caused by damage to, or weakening of the heart muscle which makes it difficult for the heart to pump properly. The damage may be caused by long-term stress on the heart caused by conditions like
high blood pressure
,
coronary artery disease
, heart defects, or sudden damage caused by conditons like heart attack or infections. At first the heart and body try to compensate by:

Beating faster—to pump more blood out to the body or lungs.

Increasing the size of ventricles—larger ventricles allow more blood to fill in. The extra blood stretches the walls of the ventricles and makes them contract more strongly.

Increasing the amount of muscle in the ventricles—at first this will help the heart beat more strongly, but eventually the extra muscle tissue can start to shrink the size of the heart chamber.

Changes in blood vessels and blood flow—blood vessels throughout the body may narrow and redirect blood flow to important organs like the heart and brain.

However, these changes only provide temporary relief and do not repair the heart failure. The heart continues to weaken and eventually the changes in the heart and body are not able to compensate for the changes.

Types of Heart Failure

The type of heart failure may be based on the side of the heart affected and current symptoms. Some examples include:

Left-sided failure:
There are two main ways that the left ventricle can fail to keep up with the demands of the body. When the left ventricular muscle is damaged, it fails to contract/pump with sufficient force. That is called
systolic failure
. If the muscle is damaged in such a way that it becomes stiff and cannot accept all the blood it needs from the left atrium, then it is called
diastolic failure
. The difference between these two types of failures is important because the treatment approach for each type may be different. In either type, when the left ventricle fails to circulate the blood, the blood can back up into the lungs.

Right-sided failure:
This occurs when the right ventricle fails to pump out enough blood to meet the body’s demand. In this case, the right ventricle and atrium cannot accept all the blood returning to the heart, and the blood backs up into the veins and capillaries. The overflow of this fluid leaks out of the capillaries to the tissue, causing edema. Edema, or fluid accumulation, usually shows up as swelling, particularly in the legs. Right-sided failure usually occurs as a result of left-sided failure. Cor pulmonale is right-sided failure caused by high blood pressure in the arteries of the lungs.

Acute heart failure:
New or worsening symptoms that appear after a stable period that may require a period of more aggressive treatment.

Congestive heart failure:
Heart failure associated with excess fluid build-up in the body, particularly around the lungs, liver, and legs.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.